The kubevirt-csi node plugin mounts the NFS export root into a temp
dir to create /data and migrate old files. That mount was hard, so
with the server gone the mkdir, readdir and rename calls on it never
returned. kubelet gives up after 2m and retries, and every retry
blocked the same way, piling up goroutines and nfs-init-* dirs.

Mount the temp root soft, so its RPCs fail once the connection to the
server is declared dead instead of blocking forever; it only does
metadata work that a retried publish redoes. retry=0 keeps mount.nfs
from retrying a failed temp mount for 2m. timeo and retrans keep their
defaults, because the first mount of a server sets them for the
connection the pods' mounts of it share. The volume mount the pod gets
stays hard, since a soft mount can report a failed write the server
applied.

Over NFSv4 that soft failure takes minutes, and a stat of a target
that is already hard-mounted can block for good, so a publish for a
target path that already has one running now returns Aborted instead
of starting another.

A soft stat can fail with EIO on a file /data already holds, and a
rename issued once the server is back would replace it, so the
migration now fails the publish on any stat error other than a
missing destination. It checks the destination with lstat, so a
user's symlink in /data that loops or dangles counts as present
instead of failing every publish or being replaced by the rename.

The skip it makes for a destination already in /data leaves the root
entry where the pod cannot see it, so it is now logged as a warning.
/data is created with a plain mkdir, since with the server gone
MkdirAll fails its stat on the mount point and then reports the local
temp dir as already existing instead of the EIO. The temp mount
errors now name the volume, like the migration errors do.

Assisted-by: LLM
Signed-off-by: Aleksei Sviridkin <[email protected]>
(cherry picked from commit f76dedf)